<?php
header('Content-Type: application/json');
require_once __DIR__ . '/../db/config.php';

try {
    $pdo = db();

    $sql = "
        SELECT 
            sr.reading_time, 
            sr.reading_value, 
            w.name AS warehouse_name,
            s.name AS slot_name,
            n.name AS node_name
        FROM sensor_readings sr
        JOIN nodes n ON sr.node_id = n.id
        JOIN slots s ON n.slot_id = s.id
        JOIN warehouses w ON s.warehouse_id = w.id
        WHERE sr.sensor_type = 'CO2'
        ORDER BY sr.reading_time DESC
        LIMIT 100; // Limit to the latest 100 readings for performance
    ";

    $stmt = $pdo->query($sql);
    $readings = $stmt->fetchAll(PDO::FETCH_ASSOC);

    echo json_encode(['success' => true, 'data' => $readings]);

} catch (PDOException $e) {
    http_response_code(500);
    echo json_encode(['success' => false, 'error' => 'Database error: ' . $e->getMessage()]);
}